Serpentine Belt Squeak

Bullseye240

Adventurer
[SUP][/SUP] SO my 06 LJ Rubicon started making a very annoying belt squeak when it rained or whenever the humidity was high. I tried a new shorter belt thinking that it would help increase tension and eliminate the squeak, no luck. I stopped by a local parts store and asked for some belt dressing as a last resort even though I knew it wasn't recommended for serp belts. The parts guy clued me into what was the root cause which I hadn't considered, the pulleys after 150,000 miles had worn down and the points of the ribs on the inside of the belt were contacting the bottom of the grooves. The result was that they lifted the rib enough that the sides were no longer in contact with the sides of the grooves reducing the "contact patch" and lowering the coefficient of friction allowing the belt to slip and make the worlds most annoying sound.

This got me to thinking of a possible way to extend the life of the system without spending a bunch of money replacing the AC, power steering, alternator and crankshaft pulleys. I decided that it just may be possible to remove the tips of the ribs without reducing the effective life of the belt. To accomplish this I too a strip of 3/4" wide by 1/8" thick and 6" long strip of aluminum with a piece of 150 grit sand paper taped to it and held it under the running engine applying gentle pressure to sand off the tips. Within seconds of this the noise stopped. I poured some water on the belt to see if it started squeaking again and no noise.

After stopping the engine I did a quick visual inspection and decided that it looked no worse for the literal wear I had just enforced upon the offending noise maker. Considering these belts have generally proven to me that they wear well for a long service life I don't think what I did will reduce it life expectancy a significant amount. I do plan on replacing the pulleys one at a time over the next few months to break up the cost a little but better. I am also curious to see if the "fix" will last very long or not. Thoughts on the whole backyard engineering service procedure?
 

unkamonkey

Explorer
It's good to think outside of the box and it sounds like you have a good parts person that told you some important information.
 

Bbasso

Expedition Leader
Baby powder works great for me it stops the squeak and lasts about 5 days period I'd only cost a dollar at the Dollar Tree stores.
 

Comanche Scott

Expedition Leader
It will probably last quite a while, as long as the tension is correct.
My one concern would be pulley thickness. It would not be pretty to have a pulley come apart.
Here is a real simple to use belt tension gauge. I've used this style for years, with great results.
They can be found on eBay, Amazon, Auto parts stores, etc..
http://www.daycoproducts.com/dayco®-belt-tension-gauges
Along with the pulleys and new belt, a new tensioner would be a great idea.

Good luck with your experiment. :beer:
 

MOguy

Explorer
I just replaced the tensioner with pulley on my TJ. Don't bother trying to change it with a Torx head. Grab a vice grab and use that. It should take about 5 minutes.
 

NatersXJ6

Explorer
you asked...

Since you requested thoughts on the backyard engineering service procedure...

I'm surprised you still have fingers. Touching a moving belt is a huge no-no. Even if you think you can do it safely, or only touch it lightly, or only touch on the side that won't suck you into a pinch point, there is a huge chance of your aluminum piece being flung into you with enough force to ruin your day.

I tend to leave well enough alone on the Internet as ar as safety goes, but I would strongly caution anyone else out there to think twice, sober up, and think twice again before trying that.

Nate
 

Kabob1865

New member
I went through this with my LJ a few months ago at 160,000 miles. I replaced the belt tensioner pulley and the idler pulley as they were starting to have a little play in them. A new genuine Mopar serpentine belt is what fixed the problem. I had another brand of belt on it that I got from the parts store. There is a difference in belt quality and it was worth the few extra bucks.
 

Bullseye240

Adventurer
I went through this with my LJ a few months ago at 160,000 miles. I replaced the belt tensioner pulley and the idler pulley as they were starting to have a little play in them. A new genuine Mopar serpentine belt is what fixed the problem. I had another brand of belt on it that I got from the parts store. There is a difference in belt quality and it was worth the few extra bucks.

Thanks for the info Kabob. This is a Gates belt and I have never had a problem with any of their belts before.

It will probably last quite a while, as long as the tension is correct.
My one concern would be pulley thickness. It would not be pretty to have a pulley come apart.
Here is a real simple to use belt tension gauge. I've used this style for years, with great results.
They can be found on eBay, Amazon, Auto parts stores, etc..
http://www.daycoproducts.com/dayco®-belt-tension-gauges
Along with the pulleys and new belt, a new tensioner would be a great idea.

Good luck with your experiment. :beer:

I think you misunderstood me, I didn't sand down the pulley, just sanded the belt ribs a little to see if it would affect the squeak. Mostly stopped it, at least cut it down enough to stop being so annoying. I'll likely order the pulleys one at a time and replace them along with the belt. I already replace both the idler pulley and tensioner assembly with no effect. I went to a slightly shorter belt and that helped for a bit but it came back.
 

Bullseye240

Adventurer
Since you requested thoughts on the backyard engineering service procedure...

I'm surprised you still have fingers. Touching a moving belt is a huge no-no. Even if you think you can do it safely, or only touch it lightly, or only touch on the side that won't suck you into a pinch point, there is a huge chance of your aluminum piece being flung into you with enough force to ruin your day.

I tend to leave well enough alone on the Internet as ar as safety goes, but I would strongly caution anyone else out there to think twice, sober up, and think twice again before trying that.

Nate

Your right I did ask for thoughts. 1 I didn't touch the belt with my fingers holding the sandpaper. 2 The pressure required to sand off perhaps a 1/16" of rubber was equivalent to less pressure than I'm using to type on this keyboard, if that much. 3 There was about 8" of belt between the nearest pinch point and my fingers were at least that far from the belt. 4 the tape holding the sandpaper to the aluminum was doing well to hold the paper in place. Honestly I was surprised when the paper didn't come loose. Thank's for the concern though, made it out all fingers intact.
 

unkamonkey

Explorer
I read your first post and understood how you did the task. A friend was the head maintenance guy at an aluminum recycling plant and decided to check the tension on the multiple belts on a compressor as it was running. He only lost around 1/2 " of his thumb.
 

Outside somewhere

Overland certified public figure brand ambassador
I read your first post and understood how you did the task. A friend was the head maintenance guy at an aluminum recycling plant and decided to check the tension on the multiple belts on a compressor as it was running. He only lost around 1/2 " of his thumb.

Shhh...I want the op to report his results from the emergency room.
 

Comanche Scott

Expedition Leader
I think you misunderstood me, I didn't sand down the pulley, just sanded the belt ribs a little to see if it would affect the squeak. Mostly stopped it, at least cut it down enough to stop being so annoying. I'll likely order the pulleys one at a time and replace them along with the belt. I already replace both the idler pulley and tensioner assembly with no effect. I went to a slightly shorter belt and that helped for a bit but it came back.
Nope, your description was very well written, and easy to understand. :)

The pulleys on the jeep are wearing. They get thinner when they wear. So you reduced the depth of the belt ribs in order to to get more life from the pulleys. The pulleys continue to wear.
I have seen where the pulley wears so thin it comes apart. This is what my warning was about.
When you finally save up enough to do the entire job, that is when you replace the belt tensioner. This way, you have a completely new system that will last a very long time with minimal maintenance.
Hope this clears up what I meant in the original post. :beer:
 

Bullseye240

Adventurer
Nope, your description was very well written, and easy to understand. :)

The pulleys on the jeep are wearing. They get thinner when they wear. So you reduced the depth of the belt ribs in order to to get more life from the pulleys. The pulleys continue to wear.
I have seen where the pulley wears so thin it comes apart. This is what my warning was about.
When you finally save up enough to do the entire job, that is when you replace the belt tensioner. This way, you have a completely new system that will last a very long time with minimal maintenance.
Hope this clears up what I meant in the original post. :beer:

Then my apologies. I only intend to run them a little while longer, next month or so before I replace them. The noise was way off the charts for tolerable anymore. I already replaced the tensioner assembly and idler pulley when it first started to no avail. I will be replacing the rest of the assembly to include the belt as soon as some funds clear up.
 

unkamonkey

Explorer
They can be a problem. I was up West of Carter Lake here in CO and around 11: 00 PM. His 80's Bronco decided to destroy a tensioner pulley. Plastic piece of crap. I called a friend who came over in his Jeep so we could get home and get a new part. Steel unit this time. About 5 minutes to fix it.
 

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